We propose a 5-year (and final) renewal of the McLean Study of Adult Development (MSAD), the first large-scale, prospective study of the long-term course of borderline personality disorder (BPD). We will obtain a maximum of 20 years of follow-up data on 290 patients who met DIB-R and DSM-III-R criteria for BPD and 72 axis II comparison subjects who met DSM-III-R criteria for another personality disorder (and neither criteria set for BPD). After 14 years of follow-up, we are still following 88% of the surviving borderline patients (and 81% of the surviving axis II comparison subjects). During the years of follow-up, we have found that symptomatic remissions of BPD are far more common and stable than expected. We have also found that these remissions were driven more by the relatively rapid resolution of acute symptoms than the relatively slow resolution of temperamental symptoms. Taken together, these findings suggest that BPD has a better symptomatic prognosis than previously known. However, we have found more guarded and complex outcomes in other areas of investigation. More specifically, we found that recovery from BPD involving good social and vocational functioning as well as symptomatic remission from BPD was more difficult to achieve and maintain than symptomatic remission alone. In addition, we found that the physical health of many borderline patients has continued to decline, with obesity-related and smoking-related illnesses becoming more common over time, particularly among borderline patients who have not recovered from BPD (i.e., those with compromised psychosocial functioning). We believe that these findings warrant further investigation into the course of borderline psychopathology (particularly sustained remissions of BPD and its constituent symptoms), psychosocial functioning, recovery from BPD, co-occurring axis I and II disorders, psychiatric treatment, changes in temperament, and medical conditions and medical treatments (AIM 1: Description). We also believe that these findings warrant further investigation into the predictors of three main outcomes: recurrence of BPD, recovery from BPD, and completed suicide (AIM 2: Prediction). Subjects will be assessed at two-year intervals by raters who are blind to all previously collected information using semistructured interviews and self-report measures, including three new instruments assessing physical pain and sleep. This proposed continuation will result in crucial knowledge about the long-term course of BPD, with direct implications for patients, their families, and the clinicians treating them. PUBLIC HEALTH RELEVANCE: Borderline personality disorder (BPD) is a common and serious psychiatric disorder. The McLean Study of Adult Development (MSAD) is the first large-scale, prospective study of the long-term course and outcome of BPD. This study will provide patients, their families, and those treating them with crucial information they need to plan for the future.